The popularity of instant scratch-off games has grown over recent years, fostered by commercial retail interests and particularly by governmental entities as a means of raising revenue. However, sales of instant scratch-off lotteries tend to fall as the public tires of similar themes. Accordingly, lottery operators attempt to introduce new concepts while utilizing the scratch-off medium. One such concept is the adaptation of the conventional Bingo game to a scratch-off game card. In this concept, the game card is divided into a "caller" area on which random Bingo numbers are covered with opaque scratch-off material, and a "Bingo-card" area on which visible randomly printed numbers appear under the B, I, N, G, and O column headings. In this concept, the player reveals the randomly printed "called" numbers by removing the opaque scratch-off compound with a coin or similar common object and compares these with the randomly printed visible numbers shown on the "Bingo Card" areas. If the player finds that five matching numbers or "Free" space form a straight line horizontally, vertically, or diagonally, as in a conventional Bingo game, or other winning patterns as declared by the particular game rules, then that game card is recognized as a winning card entitling the player to a prize in accordance with the established prize structure of the game.
This concept requires a feature in the physical structure of the game card that is not required in prior instant scratch-off lottery game cards. This new feature is one that permits the player to mark matching numbers on the Bingo card area in a convenient way that will make a five-in-a-line or other winning condition readily evident. This feature is not only necessary to assist the player in identifying a winning pattern, but the lottery agency also requires a rapid method for identifying and confirming a winning pattern presented for redemption.
One prior art means for marking cards is described by Pollard in U.S. Pat. No. 5,193,815. In this technique the Bingo card numbers are covered with a transparent or translucent scratch-off material that contains a transparent dye or pigment of a primary color, such as yellow, which appears green when covering an underlying lightly screened tint of blue. When the yellow dyed scratch-off material is removed as a covering from a printed number, the color in that area appears to change from green to blue thus indicating a match between a "called" number and that"Bingo Card" number. While effective in indicating a matched number, this method does not allow for the possibility that a player may inadvertently scratch off a non-matched number in the Bingo card area because the method of marking is not reversible or erasable by the player.
Another prior art technique for indicating a match between "called" numbers and "Bingo-Card" numbers in described by Desbines in U.S. Pat. No. 5,074,566, in which the "Bingo Card" portion numbers are first printed over a printed screen of a color or shade different from that of scratch-off material, and then covered with an opaque scratch-off material. The scratch-off material is then printed over with an identical set of numbers. When the match is seen, the player removes the uppermost number along with the scratch-off underlying that number, revealing an identical number beneath. This method, in addition to having the shortcoming of not being erasable or reversible, entails the additional manufacturing cost of an additional digitally controlled variable printing unit of an in-line web printing system in order to print the overlying numbers, and the additional controls required to prevent the potential error of misregister between underlying and overprinted numbers in the variable printing process.
Still another prior art technique for indicating a match between the called numbers and numbers appearing in the Bingo card portion of the ticket involves the use of microencapsulated dyes, the microcapsules are in turn covered by a transparent or translucent film. The player may fracture or crush the microcapsules through the film with a coin edge and release the dye of a contrasting color from inside the capsule walls. This method also suffers from non-reversiblity as well as the added cost of microencapsulation and the special equipment needed to avoid breaking microcapsules during application to the game ticket in the manufacturing process. This technique further poses the inherent problem associated with the use of microcapsules. In particular, if the microcapsules are overprotected to prevent accidental rupture during handling, then it is difficult for the user to cause their rupture. If, on the other hand, microcapsules are insufficiently or minimally protected, then frequent unintended rupturing of microcapsules during handling of the cards occurs. This techniques is therefore undesirable as it presents many drawbacks.